Agutter P S, Wheatley D N
Department of Biological Sciences, Napier University, Edinburgh, Scotland.
Bioessays. 2000 Nov;22(11):1018-23. doi: 10.1002/1521-1878(200011)22:11<1018::AID-BIES8>3.0.CO;2-Y.
For many years, it has been believed that diffusion is the principle motive force for distributing molecules within the cell. Yet, our current information about the cell makes this improbable. Furthermore, the argument that limitations responsible for the relative constancy of cell size--which seldom varies by more than a factor of 2, whereas organisms can vary in mass by up to 10(24)--are based on the limits of diffusion is questionable. This essay seeks to develop an alternative explanation based on transport of molecules along structural elements in the cytoplasm and nucleus. This mechanism can better account for cell size constancy, in light of modern biological knowledge of the complex microstructure of the cell, than simple diffusion.
多年来，人们一直认为扩散是细胞内分子分布的主要驱动力。然而，我们目前所掌握的关于细胞的信息表明这种观点不太可能成立。此外，认为导致细胞大小相对恒定的限制因素（细胞大小很少变化超过两倍，而生物体质量变化可达10的24次方）是基于扩散限制的观点也值得怀疑。本文旨在基于分子沿细胞质和细胞核中的结构元件运输提出一种替代性解释。鉴于现代生物学对细胞复杂微观结构的认识，这种机制比简单扩散更能解释细胞大小的恒定。
